Staying Dry in the Rain: Walk or Run?

Key Question

• On rainy days without a rain jacket or umbrella, should you walk or run to stay as dry as possible?

Main Concepts

Raindrop Collision

• Constant Rainfall from Above:

  • The amount of rain hitting you from above remains constant, regardless of your speed.
  • Visualize raindrops as stationary; you and the earth move upwards through the rain.
  • The volume of rain landing on top is unaffected by your horizontal speed.

• Rain from the Side:

  • If you're stationary, only rain from above hits you.
  • If you're moving, you encounter additional raindrops from the side.
  • Faster movement increases side collision with raindrops, thus getting you wetter.

Movement and Wetness

• Stationary vs. Moving:

  • Standing still minimizes wetness as you avoid side collisions.
  • Movement increases wetness due to side rain, but this is constant over distance regardless of speed.

• Snowplow Analogy:

  • Similar to a snowplow clearing snow, you encounter the same amount of rain from the side over a given distance, irrespective of speed.

Strategy: Minimizing Wetness

• Goal:
  • To stay driest, minimize the time rain hits you from above.
  • Get out of the rain as fast as possible to reduce top-down wetness.

Conclusion

• Optimal Movement:
  • Running is preferable to minimize time exposed to rain, despite increased side collisions.
  • Total wetness depends on time in rain and distance covered, highlighting the need for speed to reduce overall exposure.